ptrace: make wait_on_bit(JOBCTL_TRAPPING_BIT) in ptrace_attach() killable

ptrace_attach() can hang waiting for STOPPED -> TRACED transition if the
tracee gets frozen in between, change wait_on_bit() to use TASK_KILLABLE.

This doesn't really solve the problem(s) and we probably need to fix the
freezer.  In particular, note that this means that pm freezer will fail if
it races attach-to-stopped-task.

And otoh perhaps we can just remove JOBCTL_TRAPPING_BIT altogether, it is
not clear if we really need to hide this transition from debugger, WNOHANG
after PTRACE_ATTACH can fail anyway if it races with SIGCONT.

Signed-off-by: Oleg Nesterov <[email protected]>
Reported-by: Andrey Ryabinin <[email protected]>
Cc: Roland McGrath <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: Pedro Alves <[email protected]>
Cc: Jan Kratochvil <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions